DE10138070C2 - Piston compressor with a flow of cooling air - Google Patents

Description

The invention relates to a piston compressor with a drive unit for generating supply a rotary movement, which a compressor unit for generating Compressed air is connected, which comprises a crankcase in which a crankshaft is rotatably mounted, on which at least one connecting rod is attached, the one with Ordered piston is connected to the drive-side rotary movement in convert a linear movement of the piston to compress air is housed within an associated cylinder.

Such a piston compressor comes, for example, within a compressed air Procurement system of a commercial vehicle or a rail vehicle for Commitment. In the case of use in commercial vehicles, the Compressed air generated by the piston compressor in addition to operating the brake system ge also used to operate an air suspension system. The air suspension system includes individual air springs, which apply compressed air their spring characteristics are adjustable to an adjustable vehicle suspension realize. Because of the associated high compressed air requirements come here mostly multi-stage piston compressors are used. Through a multi-level col The high pressure can be generated within a short time interval To be able to bring about adjustment speeds of the air springs. The present However, the invention is also applicable to single-stage piston compressors.

A generic piston compressor is known from the "Lexikon Maschinenbau" (VDI-Verlag GmbH, Düsseldorf, 1995, page 620, picture 1). The single-stage piston compressor for a compressed air supply system for a commercial vehicle is driven by a crankshaft that is rotatably arranged in the crankcase. On the cure belwelle a connecting rod is rotatably mounted, which establishes a connection with a piston which can be moved back and forth within an assigned cylinder and sucks filtered air from the atmosphere via an inlet to the inside of the cylinder by the action of the piston to compress and finally provides the compressed air system of the commercial vehicle via an outlet. To control the input and the output, corresponding check valve arrangements are provided on the front side of the cylinder, which automatically act. However, this single-stage piston compressor is only suitable for generating relatively low pressures.

A generic piston compressor is known from AT-PS 157 808.

Another piston compressor is known from EP 1 028 254 A2 a two-stage compressor principle, on the other hand, is able to withstand higher pressures generate with a larger volume. For this purpose, the Compressor unit here a low pressure stage and a high pressure stage. The Nieder Pressure stage has a relatively large-area piston, which by a corres ponding cylinder arranged through filtered air from the atmosphere sphere sucks in and via an outlet after compression into the reshaped transferred high pressure stage. Because the piston of the high pressure stage with a low Ren diameter is designed as the piston of the low pressure stage, the front compressed compressed air with the same driving force to a higher pressure value be compressed. The highly compressed compressed air generated in this way is above you Output of the cylinder of the high pressure stage available for further use. To the over the compressed air flows from the low pressure stage to the high To enable the pressure stage, the two pistons work here in the push-pull principle. The Control the check valves placed on the front of the two cylinders the compressed air flow.

In the piston compressors of the type presented above takes place due to the Compression work a high heat development, especially in the area of the Zy linders instead. In the simplest case, cooling is usually done by the reverse exercise air, which only has a very limited heat when the vehicle is stationary can ensure removal. Liquid well known in the art Speed cooling for a piston compressor, however, is very expensive dig in implementation and maintenance. With the higher pressures sought here, this problem occurs in particular in the case of multi-stage piston compressors  reinforced form. The resulting high compression temperatures the compressed air also lead to an unfavorably high water absorption capacity  the subsequent drying is significantly more difficult. A high heat development be still requires the use of corresponding heat-resistant materials. in the Due to an increasing trend towards lightweight construction, however, the existing heat permanent, metallic materials are replaced by lighter plastics, wel che on the other hand due to the lower specific thermal conductivity cannot contribute to cooling in the sense of heat dissipation.

It is therefore the object of the present invention, a generic Kol benkompressor to further improve that a compressed air generation with a low compression end temperature is possible.

The task is based on a piston compressor according to the generic term of claim 1 in connection with its characterizing features. The The following dependent claims provide advantageous further developments of the Erfin again.

The invention includes the technical teaching that to improve cooling the piston compressor, an inlet-side valve is provided, which at a created by the movement of the piston vacuum in its crankcase Open position arrives to suck in cooling air, at least a second, spaced therefrom is provided outlet valve, which at an excess pressure in the crankcase caused by the movement of the piston reaches its open position to expel used cooling air, so that as a result an internal cooling air flow of the movement cycle of the at least one piston is witnessable.

The advantage of the cooling according to the invention is that it is necessary for this additional power requirement is relatively low because the air sucked in for cooling not compressed, but only against a slight resistance on the inlet side gene and outlet valve must be promoted. With usual compressors designs are entitled to between 50% and 75% of the compressor run funding  also available for cooling. The invention is not for the Kom pression used area of the piston by the additionally introduced valves for Internal cooling - especially the cylinder area - used by the on the upward movement of the piston on the back of the air sucked in when descending movement past the areas of the compressor unit to be cooled and into the area is derived. Taking into account the demand for high end pressure is at the same time with good conveying capacity and low design effort the two-stage compressor principle is particularly suitable because it also has one Intercooling of the air pre-compressed by the low pressure stage is possible. Due to the improved cooling result, the use of plastic in the Be range of the compressor unit possible because the solution according to the invention Cooling takes place due to the effect of the internal cooling air flow, and not a heat Dissipation to the outside through components made of a metal is required, which the Lightweight trend is very accommodating.

An inlet-side valve and an outlet-side valve are preferably used spring-loaded check valve for use, which corresponds to the ge desired direction of passage is installed. Such a check valve has one particularly simple construction and fulfills its function for controlling the cooling airflow automatically without further control, solely due to the housing internal pressure fluctuations. In addition, it is also conceivable that the Ven til and / or the outlet valve in the sense of active control as elect form a magnetic valve or the like, with an additional electronic control unit coordinating the opening and closing of both Valves in line with the movement cycle of the at least one piston has taken place.

To achieve an optimal cooling effect in the area of the cylinder as the place of origin To achieve supplying heat can verbes according to another, the invention Measure the at least one cylinder assigned to a liner Neten pistons, which at least partially from the internal cooling air flow  is pouring. By a correspondingly spaced arrangement of the inlet side Valve and the outlet-side valve from each other can run in such a way Cooling air flow are generated. It is conceivable to use the cooling air flow redirect additional channels running along the liner such that a effective cooling effect can be achieved.

The at least one inlet-side valve and / or the at least one outlet egg term valve can, for example, in the area of the cylinder, preferably in its frontal area, or placed on the crankcase. The placement depends on the desired cooling air flow through the crankcase as well the area of the cylinder. To ensure effective cooling air flow possible, a maximum distance of the inlet-side valve should be from inlet valve to be selected to ensure an effective for all cylinders and that To generate cooling air flow flowing through the crankcase. It is also conceivable the drive unit coupled to the compressor unit by means of a suitable connection ducts in the cooling air flow to include cooling the drive unit, for example an electric motor, through the cooling air flow enable.

According to a further measure improving the invention, the cooling air, which through the at least one inlet-side valve in the interior of the Ver reaches the seal unit, branched off directly from the intake line of the compressor unit become. This measure provides a pre-filtered cooling air supply, so that no wear-causing dirt particles with the cooling air can get into the interior of the compressor unit. Next to the junction it is also the cooling air from the intake line of the compressor unit conceivable to extract the cooling air directly from a dust-free environment men. Furthermore, it is also conceivable for the cooling air to enter the compressor pre-cool unit within an upstream active cooling unit. hereby the efficiency of the cooling can be improved.  

The used, heated cooling air can preferably be supplied via the outlet-side valve derived directly to the environment. At this point, for the purpose of Noise reduction a silencer downstream of the outlet valve be attached.

Further measures improving the invention are described below with the description of a preferred embodiment of the invention based on of the figures. It shows:

Fig. 1 shows a longitudinal section through a two-stage compressor unit of a Kol benkompressors with internal cooling air flow, and

Fig. 2 is a schematic representation of the principle of action of the inventive internal cooling air flow.

The piston compressor according to FIG. 1 consists essentially of a compressor unit 1 , which is coupled to a drive unit 2 in the form of an electric motor, which is only shown schematically here, for generating a rotary movement. The rotary movement generated by the working unit 2 serves to drive a crankcase 4 rotatably mounted in a cure bel housing 3 of the compressor unit 1 . On the cure belwelle 4 , connecting rods 5 a and 5 b are mounted opposite one another via roller bearings 6 a and 6 b. At each, the roller bearing 6 a and 6 b opposite end of the connecting rod 5 a and 5 b, a piston 7 a and 7 b is arranged with an outer radial piston seal 8 a and 8 b. Via the piston seals 8 a, 8 b, each piston 7 a, 7 b responds with an associated cylinder 9 a or 9 b. The cylinders 9 a and 9 b are made in one piece with the crankcase 3 in this embodiment and placed opposite each other accordingly. The cure belwelle 4 is accessible from the outside in the crankcase 3 via a removable crankcase cover 10 .

The piston 7 a has a larger area than the piston 7 b and is therefore part of a low-pressure stage of the compressor unit 1 . In contrast, the Kol ben 7 b is assigned to a high pressure stage of the compressor unit 1 . To generate compressed air, filtered air is taken from the atmosphere on the basis of a filter unit (not shown here) and is sucked in due to the downward movement of the piston 7 a. Here, the input-side spring-loaded check valve 11 comes into its open position. In the subsequent upward movement of the piston 7 a, the spring-loaded check valve 11 is blocked and an outlet-side, spring-loaded check valve 12 arranged in the end region of the cylinder 9 a opens. As a result, the compressed air pre-compressed in the low pressure stage passes through line 13 to the side of the opposite high pressure stage. Here, the line 13 opens into the cylinder 9 b of the high pressure stage, where an inlet-side check valve 14 is arranged, which opens when the piston 7 b moving in opposition to the piston 7 a performs an upward movement. Subsequently, the compressed air is compressed further by a subsequent downward movement of the piston 7 b and finally reaches the compressor unit 1 for further use when the spring-loaded check valve 14 is closed and the spring-loaded check valve 15 is placed next to it.

For cooling, ie for dissipating the heat generated during the compression work, an inlet-side valve 16 is provided in the area of the cylinder 9 a, which is also designed in the manner of a spring-loaded check valve. Due to its installation position in the forward direction, the valve 1 G enables cooling air to flow into the interior of the compressor unit 1 . The cylinder 9 a comprises a sleeve 21 , which cooperates directly with the piston 7 a and is flowed around by the cooling air flow. The cooling air flow then passes through an opening 17 on the cylinder 9 a into the inner region of the crankcase 3 and from here through a corresponding bore 18 into the region of the cylinder 9 b, which is also provided with a liner 19 which through the Flow of cooling air is flowing. In the end region of the cylinder 9 b of the high-pressure stage, a second, outlet-side valve 20 is provided, which is also designed in the manner of a spring loaded check valve and is connected in the opposite position to the inlet valve 16 . The consumed, ie now warmed, cooling air flow is discharged to the atmosphere.

As can be seen from FIG. 2, the spaced arrangement of the inlet-side valve 16 with respect to the outlet-side valve 20 enables optimal guidance of the internal cooling air flow, starting from the area of the piston 7 a via the area of the crankcase to the area of the second piston 7 b become. The cooling air flow is achieved by the different diameters of the pistons 7 a and 7 b during the opposite movement, which results in internal pressure fluctuations which are used by the switching of the valves 16 and 20 to obtain the internal cooling air flow. The volume flow available for the cooling air flow is excess:

(r _{low pressure} - r _{high pressure} ) ² × Π stroke × speed

So there are not used for the compression surfaces of the pistons 7 a, 7 b in cooperation with the spaced and oppositely connected valves GE 6 and 20 with check valve function for internal cooling of the United compressor unit 1 used.

The invention is not limited to the preferred one described above Embodiment. Rather, they are also constructive modifications of this conceivable, in spite of other elements designed by the following Make use of claims defined invention. In particular, the invention not limited to two-stage compressor units. The invention can also be used for single-stage or more than two-stage compressor units from Kol auxiliary compressors are used accordingly.  

LIST OF REFERENCE NUMBERS

1

compressor unit

2

drive unit

3

crankcase

4

crankshaft

5

pleuel

6

roller bearing

7

piston

8th

piston seal

9

cylinder

10

Kurbelgehäusedeckel

11

Valve, inlet side

12

Valve, outlet side

13

management

14

Valve, inlet side

15

Valve, outlet side

16

Valve, inlet side

17

drilling

18

drilling

19

liner

20

Valve, outlet side

21

liner

Claims (11)

1. Piston compressor with a drive unit ( 2 ) for generating a rotary movement, which is followed by a compressor unit ( 1 ) for generating compressed air, which comprises a crankcase ( 3 ) in which a crankshaft ( 4 ) is rotatably mounted, on the at least a connecting rod ( 5 a, 5 b) is attached, which is connected to an associated piston ( 7 a, 7 b) in order to convert the drive-side rotary movement into a linear movement of the piston ( 7 a, 7 b), which for Compressing air is housed within an associated cylinder ( 9 a, 9 b), an inlet valve ( 16 ) being provided to improve the cooling of the at least one cylinder ( 9 a, 9 b), characterized in that the inlet valve ( 16 ) at a vacuum generated by the movement of the piston ( 7 a, 7 b) in the crankcase ( 3 ) reaches its open position in order to draw in cooling air, with at least a second spaced from it inlet-side valve ( 20 ) is provided, which is at a by the movement of the piston ( 7 a; 7 b) generated excess pressure in the crankcase ( 3 ) reaches its open position in order to expel used cooling air, so that an internal cooling air flow can be generated as a result of the movement cycle of the at least one piston ( 7 a, 7 b). 2. Piston compressor according to claim 1, characterized in that the one inlet-side valve ( 16 ) and / or the outlet-side valve ( 20 ) is designed in the manner of a spring-loaded check valve. 3. Piston compressor according to claim 1 or 2, characterized in that the at least one cylinder ( 9 a, 9 b) comprises a liner ( 19 ) for the associated piston ( 7 a; 7 b) which is at least partially flowed around by the internal cooling air flow to achieve an optimal cooling effect in the area of the cylinder ( 9 a, 9 b) of the compressor unit ( 1 ). 4. Piston compressor according to claim 1, characterized in that the at least one inlet-side valve ( 16 ) and / or the at least one outlet-side valve ( 20 ) on the cylinder ( 9 a; 9 b) or on the crankcase ( 3 ) is arranged. 5. Piston compressor according to claim 1, characterized in that the at least one inlet-side valve ( 16 ) and / or the at least one outlet-side valve ( 20 ) is arranged in the region of a cylinder head ( 9 a; 9 b) associated with the cylinder. 6. Piston compressor according to claim 1, characterized in that the cooling air is branched off from the suction line of the compressor unit ( 1 ). 7. Piston compressor according to claim 1, characterized in that the Cooling air either directly from the environment or from an upstream active Cooling unit for pre-cooling the cooling air is removed. 8. Piston compressor according to claim 1, characterized in that the consumed cooling air via the outlet-side valve ( 20 ) reaches ge directly to the environment. 9. Piston compressor according to claim 1, characterized in that the used cooling air reaches the surroundings via the outlet-side valve ( 20 ) and a downstream silencer unit. 10. Piston compressor according to one of the preceding claims, characterized in that the internal cooling air flow of the compressor unit ( 1 ) via connec tion channels is also available for cooling the drive unit ( 2 ). 11. Piston compressor according to one of the preceding claims, characterized in that the compressor unit ( 1 ) is designed in several stages, the area of the at least one piston ( 7 a) of a low-pressure stage being greater than the area of the at least one piston ( 7 b) one subsequent high-pressure stage running in push-pull mode with essentially the same piston stroke, so that the cooling air flow is created by the area difference of the pistons ( 7 a, 7 b).